RESEARCH ON ANTI-COLLAPSE PERFORMANCE OF STEEL FRAME STRUCTURE WITH DIFFERENT FORTIFICATION LEVELS

Although steel frame structures have excellent seismic performance, they will inevitably collapse under strong earthquakes, resulting in enormous economic losses and casualties. In order to ensure the seismic safety of steel frame structures, the numerical modeling method of steel frame structures based on lumped plastic hinge model is introduced firstly. Then the anti-collapse ability of five-story-three-span steel frame structures with different fortification levels are analyzed using the incremental dynamic analysis (IDA) method. The results show that the lumped plastic hinge model can accurately simulate the damage of steel frame structures and can significantly improve the calculation efficiency. With the improvement of seismic fortification level, the limit value of collapse deformation capacity of steel frame structures with the same plane and elevation layout increases gradually. Therefore, it is unreasonable to evaluate the anti-collapse ability of steel frame structures with the same layout and different fortification levels using the same story drift limit value. The anti-collapse ability of steel frame structures with different fortification levels designed according to the current Chinese code meets the requirements of no collapsing under strong earthquakes, but their collapse margin ratio decreases with the improvement of fortification level.